> So far, we planned to use 18 pin female headers for the expansion > connectors J21 and J22. It turns out that 9*2 female headers are > no fun to source. It's possible, but you have to travel deep into > China for it.
What about the male connector sourcing as well, for the outsider of china want to add expansion boards? The current and new header still have same pitch right? > > 10*2 would be a considerably more common size. Switching from 18 > pin to 20 pin would be a very minor incompatibility to the J21 we > have in M1rc2 and M1rc3. Looks better then > > Now, what to do with all the new pins ? So far (18 pin headers), > the assignment looked like this, beginning with pins 1/2: > > J21: 2*5V - 2*3V3 - 6*2 signals - 2*GND > > J22: 3V3+GND - 7*2 signals - 2*GND > > Since we're already down to just three (one at the moment, but > there's some pending cleanup) unused FPGA pins in the 3.3 V > domain, I think it wouldn't make much sense to try to use the > extra pins for even more signals. I agree, more signals :-) > > Instead, I'd suggest to use them for ground, like this (20 pin > headers): > > J21: 2*GND - 2*5V - 2*3V3 - 6*2 signals - 2*GND > > J22: 2*GND - 2*3V3 - 7*2 signals - 2*GND > > Alternatively, we could separate 5V better from the rest, at the > cost of increased incompatibility of 5V-using expansion boards > and cables with pre-M1r4 units: Yes, please i try to avoid that 5V a lot but always is a risk.. _______________________________________________ http://lists.milkymist.org/listinfo.cgi/devel-milkymist.org IRC: #milkymist@Freenode
